问题
选择题
．—I did not know you were good friends．
—You___．I have known her since she moved here．You were abroad then．
A．may have
B．needn’t have
C．couldn’t have
D．must have
答案
答案：C
考查虚拟语气。句意：我不知道你们是好朋友。——你不可能知道。自从那移居到这儿我就认识他。那时你在国外。“could+have+done”是虚拟语气，表示对过去事情的假设。。故选C。